1. Field of Invention
The present invention relates to a method for producing a columnar member container for holding a columnar member in a cylindrical housing, with a shock absorbent member wrapped around the columnar member, and more particularly to a method for producing a catalytic converter for holding a catalyst substrate with a shock absorbent mat wrapped around it in a cylindrical housing.
2. Description of Related Arts
A container for holding a columnar member having a honeycomb structure and functioning as a fluid filter in a metallic cylindrical housing through a shock absorbent member has been used for a fluid treatment device, and provided for purifying various fluids. In an exhaust system of an automotive vehicle, for example, a catalytic converter, a diesel particulate filter (abbreviated as DPF) and the like have been used, and equipped with a fragile ceramic columnar member of a honeycomb structure, for a catalyst substrate, filter or the like (hereinafter, referred to as catalyst substrate). The honeycomb columnar member is held in the metallic cylindrical housing through the shock absorbent member such as a ceramic mat or the like, to constitute the fluid treatment device, an example of which is the catalytic converter. In order to produce the container for holding the columnar member such as the catalytic converter, generally employed is such a method for wrapping the shock absorbent member around the catalyst substrate, and stuffing them into the cylindrical housing, with the shock absorbent member being compressed.
For example, Japanese Patent Laid-open Publication (PCT) No. 2001-526115 proposes a method for producing a catalytic converter for use in an internal combustion engine, by wrapping a ceramic shock absorbent mat as a shock absorbent member around an outer periphery of a catalyst substrate, which are loosely inserted into a cylindrical member or stuffed (pressed) into it, and thereafter reducing the diameter of the outer periphery of the cylindrical member by means of shrinking dies, to form them in a body. In Japanese Patent Laid-open Publication No. 2002-263764, there is disclosed an apparatus for carrying a honeycomb member for use in the catalytic converter from an inserting mechanism to a drawing mechanism by means of an automatic carrying machine, instead of a hand carrying system.
In Japanese Patent Laid-open Publication No. 2003-286836, there is disclosed a method for compressing a shock absorbent mat wrapped around a catalyst substrate by a pushing member in a direction perpendicular to the longitudinal axis of the catalyst substrate, measuring a stroke when the predetermined pressure is obtained, and reducing the diameter of the cylindrical member to provide an inner diameter corresponding to the measured pressure. According to Japanese Patent Laid-open Publication No. 2003-225834, there is disclosed a method for inserting the catalyst substrate into the cylindrical member, in order not to place a longitudinal axis of the catalyst substrate oblique to or offset from the longitudinal axis of the cylindrical member. In Japanese Patent Laid-open Publication No. 11-320723, there is disclosed a catalyst substrate formed in a honeycomb structural member with hexagonal cells. And, International publication No. WO 02/095198 A1 discloses an apparatus for manufacturing a catalytic converter which is provided with a plurality of pressure roller assemblies 64 for compressing mat material and a tapered lead-in members 66, in parallel with each other.
In a co-pending U.S. patent application Ser. No. 10/637,677, filed on Aug. 11, 2003 by two of the inventors in the present application, proposed is a method of producing a container for holding a fragile substrate in a cylindrical housing with a shock absorbent member wrapped around the substrate, with an appropriate holding force determined on the basis of frictional force between the shock absorbent member and the one with the smaller coefficient of friction out of the substrate and the cylindrical housing. The method comprises the steps of inserting the substrate with the shock absorbent member wrapped around the substrate, into the cylindrical housing loosely, applying an axial load to the substrate so as to move the substrate along a longitudinal axis of the cylindrical housing by a predetermined distance, monitoring the axial load applied to the substrate, and reducing a diameter of at least a part of the cylindrical housing with the substrate held therein along the longitudinal axis of the cylindrical housing, with the shock absorbent member being compressed, to such an extent that the axial load equals a predetermined value.
According to the prior method as disclosed in Japanese Patent Laid-open Publication (PCT) No. 2001-526115, however, although nothing has been described about a carrying system of the finished catalytic converter, when a worker will carry it to a shrinking machine by hand, for example, the position of the catalyst substrate and/or shock absorbent mat relative to the cylindrical member (housing) will be shifted while it is being carried. If the diameter of the cylindrical member is reduced in that state, such a catalytic converter with the catalyst substrate held at an inappropriate position in the cylindrical member along the axis thereof will be produced. Also, the worker is engaged in the carrying process of intermediate products under production, miss-assembling might be caused, and it will take time to carry them, thereby to prolong a manufacturing time in total. According to the inserting mechanism as disclosed in Japanese Patent Laid-open Publication No. 2002-263 764, a cylinder body 3 served as the cylindrical member is secured to a fixed clamp 61, and a honeycomb member 1 served as the catalyst substrate is held by an inserting plunger 62 to be inserted into the cylinder body 3. Therefore, although the honeycomb member 1 is positioned appropriately relative to the cylinder body 3, when it is carried to a drawing mechanism 80, it will be carried in a free state, with the fixed clamp and the inserting plunger retracted. As a result, the positions of the honeycomb member 1 and/or mat 2 relative to the cylinder body 3 will be shifted due to vibration of the automatic carrying machine, and impacts or the like caused when the carrying process is initiated or terminated, so that the problem as described before will not be solved. According to the apparatus as disclosed in the International publication No. WO 02/095198 A1, although the pressure roller assemblies 64 and tapered lead-in members 66 are paced in parallel with each other, a spinning process is provided for reducing the diameter of an outer tube at a later stage separately from the inserting process as shown in FIG. 7 or FIG. 8 of that International publication.